Science

Kepler’s First Exoplanet Candidate From 10 Years Ago Is Now Official

Kepler's First Exoplanet Candidate
Image Credit: Gabriel Perez Diaz/Instituto de Astrofísica de Canarias

The Kepler Space Telescope is one of the most crucial spacecrafts for our understanding of space. It opened the door to the planets beyond our solar system, finding 3924 planets, of which 2,600 were confirmed according to the NASA Exoplanet Archives. However, Kepler’s first exoplanet candidate, first found 10 years ago, is now officially listed among the confirmed exoplanets.

Although the Kepler Space Telescope ran out of fuel months ago, marking its retirement, it left a huge legacy to future space missions, and even more data for NASA and other space agencies to work on, in order to have a better understanding of how exoplanets form and whether there might be signs of extraterrestrial life on them.

Thanks to the transit method, the telescope was able to see the potential planets when some of the light of their respective host stars was blocked as they were passing by. However, scientists didn’t find the transit method sufficient to confirm the exoplanet’s existence, which is why Kepler’s first exoplanet candidate took so long to identify.

According to NASA’s blog post, the planet was identified last month as a huge hot Jupiter, which moves fast enough to pass around its star every 3.85 days. The star appears 60 times larger in diameter compared to the Sun, as observed from Earth’s surface.

Scientifically known as Kepler-1658b, Kepler’s first exoplanet candidate had a challenging road toward its confirmation. The estimate of the planet’s host star was off, so scientists weren’t aware of the exact size of the star and the planet.

A group of scientists at the University of Hawaii and lead author, Ashley Chontos, a graduate student with the university’s Institute for Astronomy went through the Kepler data to find the right target to analyze in 2017. The work was supposed to be part of her first year research project.

“Our new analysis, which uses stellar sound waves observed in the Kepler data to characterize the star, demonstrated that the star is in fact three times larger than previously thought. This in turn means that the planet is three times larger, revealing that Kepler-1658b is actually a hot Jupiter,” Chontos said in press release. With this fine-tuned analysis, all things pointed to it being a real planet. Next they needed confirmation.

“We alerted Dave Latham (a senior astronomer at the Smithsonian Astrophysical Observatory, and co-author on the paper) and his team collected the necessary spectroscopic data to unambiguously show that Kepler-1658b is a planet,” said Dan Huber, co-author and astronomer at the University of Hawaii. “As one of the pioneers of exoplanet science and a key figure behind the Kepler mission, it was particularly fitting to have Dave be part of this confirmation.”

There have been many insights on exoplanets and stars since seeing Kepler’s first exoplanet candidate, as well as shedding light on what our sun might look like in the future. The study published in The Astronomical Journal also sheds light on difficult physical interactions which make some planets spiral toward their respective host stars.

“Kepler-1658 is a perfect example of why a better understanding of host stars of exoplanets is so important,” Chontos said. “It also tells us that there are many treasures left to be found in the Kepler data.”